Tertiary diamide based grease

ABSTRACT

NOVEL GREASE COMPOSITIONS CONTAINING MAJOR AMOUNTS OF LIQUID TERTIARY DIAMIDES HAVING THE FOLLOWING STRUCTURAL FORMULA:   R&#39;&#39;-N(-CH3)-CO-(CH2)N-CO-N(-CH3)-R&#39;&#39;   WHEREIN   R&#39;&#39; = CH3-(CH2)M-CH(-R)-(CH2)X-   WHEREIN R=N, ALKYL RADICAL HAVING C1-C5, M= 2-8, X= 1-5 ARE DISCLOSED. THESE GREASES ARE USEFUL IN A HIGH AND/OR LOW TEMPERATURE ENVIRONMENT.

United States Patent Oflice 3,827,980 Patented Aug. 6, 1974 3,827,980TERTIARY DIAMIDE BASED GREASE Robert M. Thompson, Wilmington, Del., andAlfred F. Talbot, Wallingford, Pa., assignors to Sun Research andDevelopment Co., Philadelphia, Pa. No Drawing. Filed Oct. 2, 1972, Ser.No. 293,983 Int. Cl. Cltlm 7/34 U.S. Cl. 252-28 9 Claims ABSTRACT OF THEDISCLOSURE Novel grease compositions containing major amounts of liquidtertiary diamides having the following structural formula:

wherein R=H, alkyl radical having C -C m=2-8, x: 1-5

are disclosed. These greases are useful in a high and/or low temperatureenvironment.

CROSS-REFERENCE TO RELATED APPLICATIONS This invention is related tothose described in the following listed applications:

Serial number Inventors 293,979 -R. M. Thompson. 293,980 R. M. Thompson.293,981 R. M. Thompson. 293,982 R. M. Thompson. 293,984 R. M. Thompson.

and F. E. Didot.

All of the aforementioned applications filed the same date as thisapplication. The first and second of the aforementioned applicationsrelate to classes of novel diamides, the third and fourth relate to theuse of tertiary diamides as lubricants, the fifth to the use of tertiarydiamides as swelling agents.

SUMMARY OF THE INVENTION This invention pertains to a novel greasecontaining a major amount of a liquid tertiary diamide having theformula:

and about 5-45 weight percent of a thickening agent and a minor amountof grease additive. The thickening agent can be one of the following: asaponifiable fatty material and a saponifying agent, preformed soap; thenon-soap thickeners; i.e., inorganic gel and modified clay. The greasehas particular utility in a high and/or low temperature environment.

DESCRIPTION OF THE INVENTION It has now been discovered that alubricating grease containing certain liquid tertiary diamides as aliquid lubricant is useful in a high and/or low temperature environment.

These diamides have the following general structural formula:

CH. CH;

wherein H R=CHa-( Hi)m (CHz) wherein R=H, alkyl radical having C -Cm=28, x: 1-5.

The normal parafiinic diacid of equation (1) can contain 6-14 carbonatoms; preferably 8-12. Accordingly n of the diacid of equation (1)equals 4-12, preferably 6-10. Examples of such acids are suberic,azelaic and sebacic. The secondary amine of equation (1) contains amethyl and R. The latter,

wherein x=1-5, R=H or an alkyl radical containing C -C and m=2-8. Apreferred R is one wherein x=l; more preferably 10:1 and R=H and m=3-6.Preparation of primary and secondary amines and the physical andchemical properties of the amines are given in Kirk- Othmer,Encyclopedia of Chemical Technology, 2nd edition, volume 2, Amines(Survey).

Another method involves reacting a normal paraflinic diacylhalogen, e.g.a diacylchloride, with a secondary amine wherein one radical is amethyl. This general reaction is illustrated by the following equation:

C10 0 (CHz)nC 0 C1 ZR'NHCH:

R'IIICO (CHDnCOIFIR' 2H0l CH3 CH3 In equation (2) n, as in equation (1),equals 4-12; preferably 6-10. R is the same as in general equation (1).

The lubricating grease of present invention is a solid or semi-fluidlubricant consisting of the aforementioned liquid lubricant and athickening agent and an additive. The grease contains a major amount ofthe tertiary diamide; i.e., 50% or more.

The thickening agent can be one of the following: saponifiable fattymatter and a saponifying agent, preformed soap, inorganic gel andmodified clay. The saponifiable fatty matter can be a fat or oil ofanimal, vegetable or marine origin. Also, the saponifiable fatty mattercan be the fatty acid mixture obtained via splitting a fat. Furthermore,the fatty matter can be the fatty acid obtained via chilling andpressing a distilled fatty acid or obtained via fractional distillationand solvent crystallization. The fatty acid can also be modified viahydrogenation. Examples of suitable saponifiable fatty materials arehydrogenated castor oil, hydrogenated triglycerides of ricinoleic acid,hydrogenated ricinoleic acid, hydroxystearic acids and, in particular,l2-hydroxystearic acid, methyl or ethyl esters of hydroxystearic acidand, in particular, the methyl or ethyl ester of l2-hydroxystearic acid.The saponifying agent is the material which reacts with theaforementioned fatty materials to form a soap. The agent is normally analkali. Examples of such alkalies are hydrated lime, calcium hydroxide,calcium oxide, calcium carbonate, caustic soda, sodium hydroxide, sodiumoxide, sodium carbonate, barium hydroxide, lithium hydroxide, lithiumoxide and lithium carbonate.

A preformed soap can be used in place of the saponifiable fatty matterand a saponifying agent. Use of a preformed soap in grease manufacturehas the advantage of eliminating the saponification step. One class ofpreformed soaps are also referred to as metallic stearates. Included inthe latter, in addition to calcium, lithium, barium, and sodiumstearates, are aluminum, magnesium and zinc stearates. Preformed soapsalso include metallic hydroxystearates such as lithium12-hydroxystearate.

Non-soap thickeners, as used herein, refers to inorganic gels and clayderivatives. One well known example of an inorganic gel is colloidalsilica; many others are listed and described in Manufacture andApplication of Lubricating Greases, C. I. Boner, Library of CongressCatalog Card No. 541103l. Clay derivatives refer to chemical orphysically modified clays, usually a natural clay. Organophilicbentonite is one well known family of clay derivatives and it isdescribed in detail in the aforementioned reference.

The additives can be dyes, anti-oxidants, rust inhibitors, extremepressure agents, odorizers and fillers. The latter includes graphite,asbestos, metal oxides, powdered metals, metal sulfides and carbonblack.

The advantages of a grease composition containing a tertiary diamidecompared to a petroleum lubricant based grease is that the former hassuperior physical properties at low temperature, e.g. 20 F. or at hightemperature, e.g. 400 F. For example, as discussed in greater detail inExample 2, a tertiary diamide based grease had substantially the samephysical properties at 20 F. as it did at room temperature; i.e., about70 F. By comparison, the petroleum based grease showed substantialinferior differences in physical properties at 20 F. compared to itsproperties at room temperature. As to oxidative high temperatureperformance, the tertiary diamides based grease, for example, afterbeing subjected to 400 F. for 70 hours suffered less weight loss than acomparative petroleum based grease. This last comparison is discussed ingreater detail in Example 3.

The examples hereinafter describe how these diamide greases wereprepared and their physical properties as well as comparisons withsimilar petroleum based greases.

EXAMPLES The procedure for making the greases shown in the accompanyingtable was as follows:

Example 1 92.4 parts by weight of theN,N'-dimethyl-N,N'-dioctylazelamide and 7.6 parts by weight of lithiumIZ-hydroxystearate were placed in an open container. The resultingmixture was heated and agitated until the soap melted.

After the melting occurred, the homogeneous'mixture was agitated forabout 5-10 minutes and then the mixture, with continued agitation, wasrapidly cooled. Using the same procedure, but substituting a petroleumliquid for the diamide liquid, a petroleum lubricating grease was made.The consistencies of the two greases are shown in the accompanyingTable.

The aforementioned diamide is a water-white liquid at ambienttemperature. Its kinematic viscosities were 12.36 centistokes at 210 F.and at F. a calculated 108.5 centistokes. It has a boiling point of 176C. at 0.17 mm. Hg.

The aforementioned petroleum lubricant is known also as Sunvis 51. Itskinematic viscosities are typically 11.4 centistokes at 210 F. and 109.6centistokes at 100 F. It normally has an API gravity at 60 F. of 30.0.

Example 2 90.8 parts by weight of the diamide used in Example 1, and 9.2parts by weight of lithium stearate were placed in an open container.The resulting mixture was heated and agitated until the soap melted.After the melting occurred, the molten mixture was agitated for about5-10 minutes and then the mixture, with continued agitation, was rapidlycooled. Using the same procedure, but substituting the petroleum liquidof Example 1 for the diamide liquid, a petroleum lubricating grease wasmade. The consistencies of the two greases are shown in the Table.

The low temperature properties of the two different greases prepared inthe previous paragraph were determined in the following manner. Equalweights of the two different greases were placed in separate testingdevices. The devices were suspended in a constant temperature bathmaintained at 20 F. After 20 minues, both were removed and examinedvisually for any change in consistency.

The petroleum based grease had become considerably harder than it hadbeen at room temperature. Although the grease was still stringy, thestrings that pulled away from the bulk of the grease were very short.

In contrast, the diamide based grease was only slightly more firm thanit had been at room temperature. Also, it showed about the same degreeof stringiness; i.e., as to length and number of strings, as it had atroom temperature.

This low temperature comparison of the two greases indicates thesuperiority of the diamide grease over a petroleum based grease at 20 F.

Example 3 70 parts by weight of the diamide used in Examples 1 and 2 and30 parts by weight of organophilic bentonite were placed in a containerand agitated until smooth. Subsequently, a volume of acetone equivalentto one half of the total volume of the mixture was added to the mixtureof the bentonite and diamide and agitation resumed. Shortly thereafter,the acetone completely evaporated and the grease examined as toconsistency. The acetone was added to assist the taking up of thediamide by the bentonite.

The petroleum lubricating grease was prepared in the following manner.69.7 parts by weight of the petroleum lubricant used in Example 1 wasplaced in a container along with some naphtha diluent. Also, 31.7 partsby weight of organophilic bentonite was added to the mixture in thecontainer. The resulting three-component mixture was agitated until thenaphtha evaporated. After the evaporation, a trace of iso-propanol wasadded to the mixture to assist in the taking up of the diamide by thebentonite. Also, for the same aforementioned reason, shortly thereafter,a volume of acetone, equal to one half of the volume of the total volumeof the mixture, was added to the mixture of bentonite and lubricant.After the acetone evaporated, the grease was examined as to consistency.

The consistencies of the two greases made with the bentonite are shownin the Table.

The high temperature-oxidative properties of the two different greasesprepared in the previous paragraph were determined in the followingmanner. Equal weights of the two different greases were placed inseparate testin containers. These uncovered containers were placed in acirculating air oven maintained at 400 F. for 70 hours. Afterwards, thegreases were removed and examined.

The petroleum based grease suffered a 25 weight percent loss. Theremaining materials were black, friable, lumpy solids.

In contrast, the diamide based grease suffered a 19.6 weight percentloss. The remaining material was a black, hard, lumpy solid.

This high temperature-oxidative comparison of the two greases indicatesthe superiority of the diamide grease over a petroleum based grease at400 F.

Example 4 80 parts by weight of the diamide used in Examples 1-3 wereplaced in an open container along with 20 parts of colloidal silica anda volume of naphtha equal to five times the volume of the diamide. Thecontents of the container were agitated at ambient temperature untilhomogeneous. Afterwards, the container was heated slightly to expel thenaphtha. The same procedure was followed using the petroleum liquid ofExamples 1-3 as a replacement for the diamide liquid. However, theresult was dry granules rather than a grease-like product. Bycomparison, the diamide lubricating grease was grease-like and verythick.

Example 5 80 parts by weight ofN,N-dimethyl-N,N-di-2-ethylhexylsebacamide and 20 parts by weight ofcolloidal silica were placed in an open container along with somenaphtha diluent. The three-component mixture was agitated until a smoothuniform mix was obtained. The naphtha was allowed to slowly evaporate,after which the grease was examined as to consistency. The results ofthis examina- 40 tion are shown in the table.

The diamide used in Example 5 is a water-white liquid at ambienttemperature. Its kinematic viscosities were 10.05 centistokes at 210 F.and 109.7 centistokes at 100 F. Its boiling point was 220 C. at 0.7 mm.Hg.

Greases prepared from tertiary diamides, other than those used in theexamples, will have analogous physical properties as well as greasescontaining thickening agents other than those used in the examples.

TABLE Comparison of greases prepared with petroleum or diamide lubricantConsistency of grease weight percent in grease-like. Pet, 30 weightpercent in 'amide). (4) Colloidal silica (20 Dry granu1es....;. Verythick,

weight percent). grease1ike. (5) do do Moderately firm,

smooth, greaselike, tends to lump.

1 The diamide was N,N-dimethyl-N,N-dioctylazela.mide.

2 The diamide was N,N-dimethyl-N,N-di-2-ethylhexylsebaeannde.

3 SUNVIS 51, a petroleum lubricating oil having a viscosity at roomtemperature similar to the wscosity of the diamides used.

6 What is claimed is: 1. A lubricating grease composition consistingessen tially of: i (a) a major amount of a tertiary diamide having theformula:

wherein wherein R=H, alkyl radical having C -C m=28, x=1-5;

(b) about 5-45 Weight percent of a thickening agent selected from thegroup consisting of saponifiable fatty matter and a saponifying agent,preformed soap, inorganic gel, and modified clay; and

(c) a minor amount of grease additive.

2. Composition according to Claim 1 wherein the diamide isN,N'-dimethyl-N,N-dihexylazelamide.

3. Composition according to Claim 1 wherein the diamide isN,N'-dimethyl-N,N-dioctylazelamide.

4. Composition according to Claim 1 wherein the diamide isN,N'-dimethyl-N,N'-di-Z-ethylhexylazelamide.

5. Composition according to Claim 1 wherein the diamide isN,N'dimethvl-N,N'-di-2-ethylhexylsebacamide.

6. Composition according to Claim 1 wherein the preformed soap is ametallic stearate.

7. Composition according to Claim 1 wherein the inorganic gel is acolloidal silica.

8. Composition according to Claim 1 wherein the modified clay is anorganophilic bentonite.

9. Composition according to Claim 1 wherein the thickening agent isselected from the group consisting of lithium 12-hydroxystearate,lithium stearate, organophilic bentonite, and colloidal silica; and thetertiary diamide is N,N'-dimethyl-N,N-dioctylazelamide.

References Cited UNITED STATES PATENTS 4/1967 Low et a1 252-515 A 7/1971Coshburn 252-515 A US. Cl. X.R. 252-42.4, 51.5 A

